1. Field of the Invention
The present invention relates to a microcomputer having a user mode interrupt function and a supervisor (SV) mode interrupt function.
2. Description of the Related Art
In a microcomputer, in order to debug an applied system, an in-circuit emulator, i.e., a supervisor mode interrupt control circuit is provided in addition to a user mode interrupt control circuit. This will be explained later in detail.
In a prior art microcomputer, an SV mode interrupt has the highest priority, that is, the SV mode interrupt has the highest priority over any of user mode interrupts. Therefore, when an SV mode interrupt occurs, any user mode interrupt. In addition, during a time period where an SV mode interrupt is carried out, any user mode interrupt is prohibited, which may destroy the system.
Further, in the prior art microcomputer, the content of a program counter and a processor status word are stored in a stack (memory) both during a user mode interrupt and an SV mode interrupt, which may restrict the region of the stack for the user mode interrupt processing.